Targeting gold at the end of the rainbow: surgical gamma probes in the 21st century.

Surgical gamma detection probes (GDPs) have become important in the surgical management of neoplastic disease in the past 20 years. Their history and radiophysics are discussed, with consideration of the overarching issue of tumor-to-background ratio (TBR). GDPs are currently most commonly used in sentinel node applications in a variety of tumors. Whether their role in clinical surgical practice can be extended to other applications will depend on the development of radiolabeled tumor marking agents which have much improved TBR, and parallel developments in oncology research which may overtake this technology.